Delta and JetBlue say customers with Tuesday or Wednesday tickets for flights to, from or through several Northeast airports will be able to make a one-time change to their itineraries without the standard change fee. Fliers changing their flights must complete their rebooked travel by Friday (Aug. 15).

Alternatively, Delta customers wishing to reschedule their trip beyond Friday will not be charged a change fee, but they will have to pay any fare difference that may result from the new itinerary. Some additional restrictions may apply, which the carrier outlines on its website.

Delta's flexible rebooking policy includes flights at the following airports: Baltimore; New York JFK, New York LaGuardia; Newark Liberty; Newburgh/Stewart, N.Y.; Philadelphia; Washington Dulles; Washington Reagan National and Westchester County/White Plains, N.Y.

United's flexible rebooking policy is a bit more restrictive, applying only to Tuesday flights at the following airports: New York JFK, New York LaGuardia, Newark Liberty, Philadelphia and Westchester County/White Plains. United will waive the rebooking fees for most customers wishing to make a change, but it says "a difference in fare may apply" to certain travelers.

The airlines' waivers come as forecasts call for a storm to dump up to 3 inches of rain or more on large parts of a region that stretches from the mid-Atlantic into the New York City area. The National Weather Service has issued a flash flood watch for New York City and the surrounding area. Heavy rain and flooding is possible Tuesday into Wednesday.

More broadly, the region is home to some of the nation's most delay prone airports. Among those are the three big New York City airports â?? JFK, LaGuardia and Newark â?? and Philadelphia, each of which can see long, widespread delays during even minor weather events.

Delta has a hub at two of those airports, operating a domestic-focused hub at LaGuardia and an international-focused hub at JFK. United counts Newark Liberty as one of its biggest hubs. JetBlue operates its busiest hub at New York JFK and has its second busiest hub at Boston, which also is expected to see stormy weather.